attack on avengers
by hug the ents
Summary: when shield headquaters is attacked by a mysterious group of terrorists, its up to the avengers to solve the mystery, even if it means associating with the enemy. slightly au.
1. Chapter 1

submission

Avengers and attack on titan crossover

Chapter one

Intro

Tony stark felt invincible. He grinned as the metal claw carefully sketched a photo of pepper. He had been working on this artist drone for months, but it was totally worth it.

Working in the hi-tech lab at SHIELD HQ was always something to look forward to. Hell, they had stuff here even he hadn't invented. He smiled slightly to himself as he pocketed two newly developed oxygen conductors. They would come in handy when he was working on the model twelve….

"Put them back stark" tony groaned as he turned out his pockets. "You're no fun director" nick fury gave him an evil look. "Those cost at least ten thousand dollars each, have some respect"

Tony shrugged, doing his best to raise the director's ire. Fury sighed. "Quit whining stark we've got a real problem on our hands. Now hurry up and report to control".

Tony slouched past the director and into the hall. That dick ….. He sighed to himself.

It was when the sound of alarm bells reached his ears that tony finally realised that something was wrong. He began to walk more quickly, eventually sprinting. By the time he reached head control, people were rushing past him and sirens were sounding.

He yanked the door open and stepped inside. Bruce banner turned to face him. "Thank god you're here tony; we have one hell of a problem". Tony gazed upwards to the main screen. Information was streaming across it. What the hell was this?

"Tony, listen to me" banner's voice interrupted his thoughts. "Stay focused. Headquarters has been breached by a group of what we assume are terrorists and are destroying valuable research and killing our agents. The only reason we aren't attacking them right now is this".

Banner brought up a picture of a green cloaked figure on his ipad. "You see this guy? We ran a biological scan on him five minutes ago. The scan confirmed his as not human, but doesn't know what species he is. This is serious tony, that scan has records of every creatures ass in the universe, and quite a few outside it.

That's what we're worried about. This guy is probably incredibly dangerous, and he isn't the only one. Have a look at the security camera feed from two minutes ago". Tony watched as banner played a video on the screen.

An agent was shooting at a green cloaked figure, which seemed to be female judging by her body shape. The agent fired six bullets at her, all of which were blocked using what seemed to be double steel blades.Eyes widened in shock. This girl was deflecting bullets using… swords?

Tony's eyes turned back to the video. The girl was moving closer and closer to the agent, who was desperately firing bullets in her direction, to no avail.

The girl did a front flip right over the man, landing behind him. He attempted to turn around to face her but at the last moment she crossed her blades and decapitated him from the back of the neck, his head tumbling to the ground. The video ended.

Tony was shell-shocked. That girl just demonstrated skill that could probably rival Natasha Romanov as if it were nothing. He was still contemplating this when the floor blew up in front of him, sending him flying backwards and into unconsciousness.


	2. Chapter 2

Chapter 2

Attack on avengers

Tony groaned as he opened his eyes. He could feel the rubble beneath him,crushing his body slowly. He closed his eyes in pain and gritted his teeth as he pulled.

Almost ten minutes of wriggling about and feeling generally humiliated, he had manged to remove his upper body entirely from the broken pile of bricks. He groaned again as he realised that at least one of his legs was broken and possibly his kneecap.

He had just begun to think about all the crap pepper was going to give him over this when he heard the crash of a door nearby. He frowned and listened. He could hear someone cursing rapidly in another language. Japanese?

Before he could shift out of sight, a green cloaked head peeked out at him from behind a destroyed bank of computers.

The figure stepped out fully, and tony swore to himself that that was most definitely the most sexual uniform on the planet. It consisted of a cloak, white pants, and far too many leather straps and buckles. He cursed to himself as he tried to move… this person could dangerous. The person moved closer, unsheathing a long, segmented steel blade.

Tony felt himself struggle move desperately. The figure shot forward suddenly and then the blade was at his throat, cutting into his skin. Tony stark closed his eyes. Fuck this. This was probably the end. Well shit.

Tony felt something large crash into the figure, knocking them clean away from him.

The figure snarled, their face now visible. A halfway-hulk Bruce banner snarled right back.

Tony studied the figure. She was a girl of about sixteen, her black eyes darting furtively around her. Her brown hair had come lose from its ponytail and was swept across her face. A few freckles were smattered across her cheeks. She also looked absolutely murderous. The pair were circling each other, Bruce now completely hulk.

Tony almost felt sorry for the girl.

She wasn't going to survive this fight. He decided to help. "Hey! Hey you!" the girl turned to face him, looking confused. "if you surrender now, ill make sure he doesn't hurt you" tony called out.

The girl looked at him disbelievingly and then she began to laugh.

She was still laughing when she brought her hand to her mouth and bit down, hard.

Tony felt himself blown back by an explosion. Lightning crackled around the area where the girl stood, and steam billowed out in all directions. He righted himself and squinted back to where the pair had been moments ago.

What he saw next made his eyes grown so wide, his eyeballs might have fallen out. A large, hulking creature stood where the girl had been moments ago. He realised with shock that it was- or had been- that girl from before. It had black straggly hair, black eyes, pointed teeth, a hooked nose and generally looked like a creature from the depths of hell.

Tony edged away carefully, trying not to scream. he was seriously regretting his life choices at this moment, that…thing was fucking terrifying. His brain, being the absolute genius it was, noticed something almost subconsciously. He thought back to seconds before the girl transformed.

Her body shape… her posture… it was different. Different from the girl in the security feed. That meant there were at least three incredibly dangerous adolescents running around creating havoc, and he didn't know where the other two were.

Searching frantically around for anything that might help him escape or let him live longer, he cursed himself for not bringing the handy tracking bracelet he had used in New York with him. His eyes landed on a small walkie talkie, a plan formulating inside his brain. He glanced over to hulk and..thing, who were clawing at each other at this point, hulk having pinned the thing down but thing having clawed one of the hulks eyes and his shoulder clean off, her sharp nails now embedded in his calf.

At this point tony was very worried for his friend, but knew there was nothing he could do while without his goddamn suit. He took a deep breath and sprinted over to the overturned cabinet that the walkie talkie was currently situated. He grabbed the walkie talkie, only to drop it in surprise when it crackled to life in his hands.

The distressed voice of Steve Rogers came though. "I repeat. We are sending backup to floor twelve sections four an five" tony almost laughed in relief. Command was situated on the edge of section five. He let out a breath he hadn't realised he'd been keeping in.

Tony turned back to where the thing and the hulk were fighting. The thing-he was gonna call it that from now on- had gained the upper hand and was ripping green flesh off in chunks. Tony had never seen anyone even get close to besting the hulk…

The thing, in a burst of strength, threw the hulk across the room and into a bank of computers. It snarled in pain and fell to its knees. Tony felt himself holding his breath.

Suddenly it lunged at him, only to be stopped by a shower of gunfire from near the door. "tony!" tony heard Steve's voice calling at him from across the room. He stood up and made his way towards his (very) patriotic friend. The thing was on the floor struggling to stand up. Steve threw his shield at it, embedding the edge in its skull. The thing let out an animalistic howl of pain, falling to the ground and not moving.

Steve was just about to approach the creature when he saw movement at the base of it neck. The girl from before crawled pitifully out of the base of its neck, covered in muscle and blood. Tony was more than surprised to see her smile slightly, and give him a small salute before slipping into unconsciousness.

Oh they were so fucked


	3. Chapter 3

Hi guys. Im so sorry because this is incredibly late and I really have no other excuse except for procrastination. I'd like to than everyone who followed or favourited or reviewed so far, it means a lot

Attack on avenger's chapter 3

"Stark"

"Stark"

Tony opened his eyes groggily. A bright white light shone right into his eyes, causing him to rub them in pain.

He groaned. Unconscious twice in less than an hour. Pepper was going to kill him. He felt a sharp pain in his arm. Tony hissed and opened his eyes. A grim-faced Clint Barton tutted. "Don't be such a baby stark". Tony muttered a standard sarcastic insult in reply.

Clint stood back and covered tony with a hospital blanket. "You passed out halfway to the helicarrier, Steve had to carry you here". Tony flushed. Now that was embarrassing. "You also have a collapsed lung, crushed ankle and a severe concussion. Well done" tony groaned again. Great he wasn't walking any time soon.

"Barton" tony said hoarsely. "What happened while I was out? Where are the others?"

Clint hesitated.

"well we caught the intruders. There were five of them. And they managed to temporarily put headquarters out of action, disable all our communications with Europe and take out over sixty of our best agents, including Steve.

Tony sucked in a shocked breath. Steve Rogers, out of action? How…?

"one of the hostiles managed to get past his defences and severed his entire hand".

Tony was in shock. How did they manage to beat Steve?

"tony, listen. This is the important part. Steve kept going after that punk got his hand. He grabbed that kid's blade and used it to slice him open, sternum to hip. However, when we cuffed him later the injury was gone. It had healed completely. Those things aren't human stark"

Tony grit his teeth. "So we find out what they are then. Where are they being held?"

"in the same prison we used for Loki".

Tony nodded. Barton seemed to get what meant and said something along the lines of "ill go get a wheelchair"

At that moment tony put his head in his hands and cursed that goddammed captain for being all heroic and letting himself get injured like that.

Barton returned and silently helped tony into the wheelchair. "Fury just called to say the interrogation begins in twenty minutes. We should go" tony nodded and clenched his fist. He was going to make those brats pay.

By the time they reached level zero, most of the rest of the gang had congregated.

Natasha stood in the corner, frowning. Bruce sat, head in hand, the other in a sling. Thor was not present, and neither was Steve, obviously.

They had been waiting for exactly seven minutes and twelve seconds when nick fury strode out of a nearby lift, followed by agent Maria hill. He nodded to everyone present, and gestured for two guards to open the door into the prison room. The small group made their way into the room, all of them on their guard.

Tony took in a deep breath and rolled his wheelchair through the doorway.

Tony gazed across the room, his eyes barely noticing the several armed guards situated at every corner. His eyes finally landed on the glass cage, and its contents.

He almost felt sorry for the five bedraggled figures, but then he was reminded of Steve and what they had done and he grit his teeth. Nick fury motioned for most of the guards to leave, which they did, albeit unwillingly and with several untrusting glances towards the glass cylinder.

Tony heard the director clear his throat. "Can you tell us your names?" he asked simply. A brown haired boy looked up. He shrugged. "I don't see why not. It's not going to make it any easier for you to stop us. I'm Eren jaeger, that's Bertholt furbar, Annie leonhardt, Reiner braun and Ymir".

Tony noticed that each as each teens name was called out, they raised their head. All of them seemed fairly bored with the situation, except for Bertholt, who was sweating nervously but still looked dangerous. Tony swallowed and studied the teens

The boy who had spoken-eren-had brown hair and eyes and wore an expression that simply stated 'I'm okay now, but if you anger me I'll rip your body into pieces and string them out as decorations'

Bertholdt was tall, dark haired and generally looked like the kind of person who you never really noticed until they were right in front of you. Tony almost felt sorry for him.

He moved on to the girl sitting next to him. His heart nearly stopped. Could it be?

It matched… it was none other than the very first of the five he had seen, the girl from the security camera footage. Annie- if he remembered correctly. Blonde, short with a permanent scowl fixed upon her face.

The boy next to her looked like the very essence of your typical high school jock. Big, blonde, well built and a tendency for violence. Tony was pretty sure he was Reiner.

The last teen was of course ymir, the creepy possible-hulk girl.

" Mr jaeger, can you tell us exactly was species you are? You aren't human, for sure"

At this every member of the group smiled slightly.

"No sir we definitely aren't human" came the voice of reiner for the first time.

Eren nodded "no. not human. Titan


	4. Chapter 4

Chapter 4

Tony scratched his head confusedly. What did the boy mean by 'titan'? Maybe he was referring to the Greek myths? "do you mean as in the titans from Greek mythology?" Natasha questioned, voicing his thoughts.

The blonde girl-Annie- snorted. "What the fuck is Greek mythology?" she said harshly. The others nodded in agreement.

Tony frowned. Nick sighed and typed something into his phone. "So can you tell us what a titan is them, Mr. Jaeger?" fury asked commandingly.

The brunette shook his head and smiled. "Sorry, it's classified". He said, almost mockingly

Fury sighed again. "Very well. You leave me with no other choice. Agent hill, prepare the interrogation room and notify Bruce banner". The young woman nodded and left.

Fury turned to Clint Barton. "Agent Barton, please go up to level twelve and ask doctor wainwright to send a resource team of twenty doctors for the experiments". Tony noticed that at the word experiments, all five teens looked utterly horrified and cringed away.

Fury turned back to the glass prison. " you wil all be subjected to a standardised interrogation, I recommend that you come along quietly, as we really only need one of you in order to conduct experiments. At this bertholdt and reiner paled a little, but eren shrugged and annie looked like she was going to laugh.

Fury gestured for ten heavily armed guards to open the door of the prison. Natasha then strode forward and began to remove berthodlt's bindings, all except for his handcuffs. She shoved the boy to his feet and towards the exit. Tony, fury, bruce and about twenty guards followed.

The interrogation room was the single most secure room on the ship. No one could hear you inside as the entire room was completely sealed off and even need to be supplied with air from gas tanks inside the room. Natasha dumped the lanky teen unceremoniously into a chair and began trussing him up once again.

The entire room was quiet, there only being six people present. Tony, Natasha, Clint, fury, hill and Bruce who was fiddling with some syringes on a cart. "Doctor banner, the serum please" fury said in a commanding tone.

Bruce nodded and handed fury a syringe filled with a clear liquid. Fury examined it for a moment, then shot forward and stuck it into Bertholdt's arm. The teen grimaced in pain as the liquid surged through his veins. Fury stepped back. "That was dangerous, director". Hill said quietly.

"The serum has only been tested theoretically….that could have killed him". Fury looked regretful for a second, but it then vanished, replaced with a hard expression.

"We'd still have four more".

Sorry this is a really really short chapter I promise ill have a new one up soon. Thanks for all the follows and favourites!


	5. Chapter 5

Chapter 5

Tony watched with slight horror while the boy's body began to convulse under the effect of the serum. Bertholdt strained against his bindings, his eyes wide with fear and his mouth frothing slightly.

Eventually his muscles relaxed and he slumped down on the table. Fury eyed him warily. "Mr Fubar"

No response

Fury nodded to Natasha, who yanked the boy by his collar and pulled him up to face her. Bertholdt looked both slightly insulted and a bit frightened. He shook himself free of her grip and gazed towards fury, who was scanning a clipboard filled with possible questions.

The director licked his lips, and then spoke.

"Bertholdt fubar, can you tell me what a titan is?"

The boy instantly reacted to the question. He swallowed nervously and sweat began to run down his face. He seemed to be trying his very best not to blurt it out, but in the end his heavily drugged mind let him down.

"Titans are a race of humanoid giants whose only desire is to devour humans. Titans greatly resemble human beings in that they are bipedal creatures with the same number and arrangement of limbs and features one would expect in human beings. They are all deformed by human standards to a greater or lesser degree, ranging from minor abnormalities in proportions (enlarged head, small limbs etc.) to apparently lacking skin and subcutaneous tissues, although they do not bleed from such deformities, indicating that they perhaps possess some other mechanism to compensate for this. The vast majority of Titans are masculine, although all Titans lack sex organs, and their method of reproduction is currently unknown.

Titans almost universally possess widened mouths with an enormous number of small, square teeth, though some have been known to possess only canines. Still, the majority of Titans have been shown to lack canines, although possibly not incisors and use incisors in their primary activity – eating humans. They apparently do not possess a complete or functioning digestive tract, merely a stomach-like cavity that eventually fills up with what they swallow, forcing them to regurgitate after consuming a certain amount before being able to continue eating more humans they encounter in their rampage".

The answer boy gave sounded dead and overused, as if learned years ago in a dusty classroom, as information to be forgotten as soon as the bell rang.

Bruce, tony noticed, had been taking notes on everything the boy had said. Suddenly he stopped. "But", he asked cautiously, "there has been no recorded evidence of these creatures from any myth. Does this mean you are from a different planet or dimension?"

The boy looked puzzled at first but soon understood. "I believe myself and my…comrades were tossed through some sort of portal. I can't be sure it happened so fast". Bruce nodded. Fury cleared his throat. "This serum wears off in the next forty seconds so we can only ask one more question"

Bertholdt fubar, you have killed multiple people in the last two hours. As we can assume you have a similar ability to your comrade, you better tell us whether you have killed people in that form and how many".

Suddenly the boy's calm demeanour shattered. He lurched forward, hands in his mouth as if he was going to be sick. He muttered something intelligible and Natasha repeated her earlier action and yanked him up. He was curled up, as if he didn't want to be hurt. Natasha brought the boy up to her face and listened to his ramblings. Her face grew pale and she shoved him back down. "what is it Romanov?"

She looked up as if just noticing her commander for the first time. "Nick…. He's reciting their _names_"

Tony moved closer. Reciting their names? What did he mea-….

"marco bott, marcel, hannes, mina Carolina, Thomas wagner, nic tius, ian dietrech, franz, mitabi jarnach, mylius zeramuski….."

Tony stood back in shock. _Oh my god_, he thought. _The guys insane._


	6. Chapter 6

This is a super super short chapter I know but im working on writing more! Im sorry I left this story alone for so long, its been quite a busy year!

Nick fury massaged his temples tiredly as the now-screaming teen was dragged away, to be placed in solitary confinement until further notice. Natasha saw his exhausted look and gave him an uncharacteristic pat on the back. He inwardly raised and eyebrow at her acrtion but said nothing. The boy's evident insanity seemed to have shaken her up a bit, which was certainly disconcerting. A doctor entered the room quietly. 'director fury, sir, should we proceed with the interrogation?

Fury sighed. Right now his head was pounding painfully and all he really wanted to do was go lie down somewhere dark and warm. But duty called, and as much as he loathed the idea of dealing with more insane non-humans, he had to get to the bottom of this in order to protect himself and his organisation.

He nodded curtly to the doctor, who took this as a yes and jotted something down on a clipboard.

Moments later, the blonde female (annie? He couldn't remember at this point) was led into the room. Her expression was unreadable and she hardly seemed to notice the thick chains that coated her entire body. She sat down in the chair and allowed her bindings to be tied down more securely without complaint, and instead fixed fury with a mildly puzzled, mildly offended look, as if to say, almost mockingly, 'you don't trust me?' fury averted her gaze and instructed one of the doctors to prepare the serum.

She didn't react to the needle piercing her arm, nor fury slamming his hands down on the steel table in his best 'bad cop' impression. It only took a few minutes for her to start coughing up blood, however. Natasha's eyes widened slightly when she noticed the blood trickling down the girls chin as she forced herself to remain impassive. Huge sobs of pain made her body tremble, but she didn't make a sound. 'fury' Natasha said quietly to the man who looked just as confused as her. 'I think its wrecking her system. We need to help her or shes going to die'. Fury nodded, not taking his eyes off the girl, who had given up on trying to conceal her pain, and was leaning back in her chair, eyes rolling back in her head as she hacked up chunks of congealed blood.

Two white-coated doctors grasped her firmly by the upper arms as fury gave the command, and in minutes the only evidence the girl had ever been there was the blood, which was quickly being cleaned up by the security guard. Fury heaved in a deep breath. He really really really hoped that girl lived, because something was telling him her friends wouldn't be too pleased if she didn't.

Hmm sorry its that short… thank you so much for all the reviews and favourites/follows! It really means a lot to me!


	7. Chapter 7

**I'm really sorry for not updating, I'm currently in an exam year so I have all sorts of fun things like study and art portfolios and science reports and crying to do. Ah, such fun. **

**My main junior cert exams are coming up in a month so I'm not going to be able to update regularly (not that I have been in the first place), but once i get my summer holidays I'll be working hard on my stories, specifically my hetalia and avengers one. this chapter is painfully short but it's all I can offer as my free time is very limited these days. enjoy, and please review if you can. **

chapter 7

Clint sighed and gazed over towards the blonde figure lying in the starched white hospital bed. He ran a hand through his brown hair and sighed again, this time eliciting a response from a mildly irritated Maria hill, who raised an eyebrow at him before going back to whatever she was researching. Clint made a face at her and leaned backwards, putting his arms behind his head and stretching. Of course _he_ would be the one assigned the incredibly boring task of 'watch the half-dead monster teen and make sure she doesn't maim anyone'.

Speaking of monster teens, the one he was currently supposed to be guarding was waking up, groggily rubbing her eyes and observing her surroundings. She seemed fascinated by the texture and design of the plastic-like hospital gown she was wearing, and even more intrigued by the IV catheter embedded in her wrist. She tugged at it and narrowed her eyes in silent frustration when she couldn't find out the use of the irritating needle.

Clint watched her with slight fascination. Her reactions and interpretations of the world around her were so childlike and innocent that he had trouble believing she was the bloodthirsty monster that he had seen in the camera footage. Maria caught his softening expression and narrowed her eyes.

'Don't let her apparent innocence fool you, Barton they're about as heartless as it gets'. She eyed the exploring teen with distrust and thinly veiled hatred.

'I saw her kill Mike DeLaurentis without a single drop of mercy'. She drew her finger across her neck for added effect. 'Completely decapitated him in five seconds'.

Clint watched the blonde thoughtfully. 'Maybe they're like those guys we dealt with last year?' he scratched his chin. 'You know the ones with that could manipulate shadows and summon monsters and things? They were scarily powerful, but from what I saw they didn't really know what they were doing. They were confused and scared. Fish out of water.'

Maria shrugged. 'I was stationed in Yemen at the time I wouldn't know'. She seemed to look thoughtful for a minute but the expression was gone seconds later.

'Regardless of what they're going through, they're still a threat and therefore should be treated as such. Now come on, I think Romanov volunteered to take the first night shift, which leaves you with a four hour rest period before you're back on duty'

Clint raised an eyebrow but left all the same, a haunted-looking Natasha almost stumbling through the door a few minutes later. She practically fell into the chair and looked at Maria with a blank expression, as if just realizing the brunette was there.

'Rough evening?' Maria asked, not looking up from her laptop. Natasha sighed and nodded, running a hand through her auburn curls. 'They're all insane'. She said with finality. 'They're insane and they're dangerous and _brutal'_.

Maria raised an eyebrow. 'And that's a surprise?' Natasha nodded reluctantly. 'It's a surprise because they're just kids I suppose' she said eventually, then shook her head.

'I can't let that get in the way though' .With that she got up and stood near the reinforced glass that separated her from Annie Leonhardt.

'You don't like them because they remind you of yourself' Maria murmured quietly, too quiet for the disturbed Russian to hear, and turned back to her work. Those reports wouldn't write themselves.

**So that chapter was so short i almost cried updating it honestly. I'm so busy but I'll try and have something else up before the end of the month. **

**In case anyone was wondering, Natasha has just witnessed the interrogation of Reiner, which happened while Annie was out.**

**I love playing with marias character, as my interpretation of her is as a conflicted character with a very black and white sense of morality, which clashes with Clints because he sees it as a bit more of a grey area. **

**anyway I'll try and get Reiner's interrogation up before the end of the month, but my fading interest in snk and the fact that I have to study for exams means it might not happen.**

**reviews are greatly appreciated, especially ones that give constructive criticism or pointers on how to improve! **

**(also I apologise for my atrocious grammar)**


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